Below:
On Tue, Sep 9, 2008 at 12:47 AM, bill lam <[EMAIL PROTECTED]> wrote:
> OS should dynamically switch core for each process. Yet it is possible
Only where warranted: usually lighter loaded core
(offset by some % of various resources
to allow for task/process/core switch overehead)
(CPU, main/cache memory hits), thread/process relative priority)
>
> to tell os which core should be used.
> Google for "cpu affinity" should give the some examples.
Yes, affining will improve WSS hit percentage dramatically:
used correctly.
Bettter algortihms in the OS will also override affining, too.
But none of them will subpartition a grid/array algortihm into
interval/area subcomputations:
all of the abover onyl apply when there IS a way to dissect into
subthreads or processes:
but this in turn defeats the inherent power of J to a large extent:
You can no longer easily obtain the internal optimizations
(or those gained by proper analytic application of the mind using J)
across just those boundaries within J:
you have to explicitly re-include them at each such wall.
Not a problem where there are NONE or few such gains.
Typically this will be the case (or apparently so)
at just those boundaries for independent (sic) interactive processes or
threads.
>
>
> On Mon, 08 Sep 2008, Devon McCormick wrote:
>
> > It seems to me that the OS is smart enough to put new processing on the
> > less-loaded core. I find the advantage of two cores as opposed to one is
> > that while I'm running a CPU-intensive J-app, I can still do other work
> with
> > no noticeable slow-down. When I run the same J-app on a single-core
> > machine, it becomes very hard to use for anything else.
> >
> > I'm guessing that you could fire up three independent J-apps on a
> quad-core
> > and that each would run on its own core, leaving the fourth free to do
> > important things like read Slashdot and respond to the J-forum. However,
> I
> > lack a machine on which to test this hypothesis.
> >
> > On 9/8/08, Alex Rufon <[EMAIL PROTECTED]> wrote:
> > >
> > > I was able to do what Devon described accidentally. I built a windows
> > > service which spawns an instance of J for each client connection. The
> > > machine was a Compaq server with multiple CPU's running on Windows 2000
> > > Advance Server. I never really intended it to run J on multiple-CPU's
> but it
> > > does. :)
> > >
> > > Still, I don't do interprocess communication and each J session is
> atomic
> > > with all its data and script. Oh, I did some observation and the OS
> > > assigning which CPU is I believe arbitrary ... although the first few
> > > instances of J would always run on CPU-0.
> > >
> > >
> > > -----Original Message-----
> > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> On
> > > Behalf Of Devon McCormick
> > > Sent: Monday, September 08, 2008 7:20 PM
> > > To: Chat forum
> > > Subject: Re: [Jchat] parallel processing in J
> > >
> > > Hi -
> > >
> > > I don't think this is a J issue. I've been able to make use of both
> cores
> > > on my dual-core machine by running separate instances of J - it looks
> like
> > > the OS handles this. Try running CPU-intensive tasks on multiple
> versions
> > > of J simultaneously.
> > >
> > > Regards,
> > >
> > > Devon
> > >
> > > On 9/8/08, Matthew Brand <[EMAIL PROTECTED]> wrote:
> > > >
> > > > Hi All,
> > > >
> > > > I don't know much about the subject but when I look at task manager,
> the
> > > > CPU
> > > > usage only goes up to 25% on the four core processsor. Is there a
> > > > configuration that makes J use all the cores?
> > > >
> > > > As I say, I don't know much about it but does this mean that it
> should be
> > > > possible:
> > > >
> > > > >From
> > > > >http://en.wikipedia.org/wiki/J_(programming_language)<http://en.wikipedia.org/wiki/J_%28programming_language%29>
> <
> > > > http://en.wikipedia.org/wiki/J_(programming_language<http://en.wikipedia.org/wiki/J_%28programming_language>
> >:
> > > > "Being an array programming
> > > > language<http://en.wikipedia.org/wiki/Array_programming_language>,
> > > > J is very terse and powerful, and is most suited to
> > > > mathematical<http://en.wikipedia.org/wiki/Mathematical>and
> > > > statistical <http://en.wikipedia.org/wiki/Statistical> programming,
> > > > especially when performing operations on
> > > > matrices<http://en.wikipedia.org/wiki/Matrix_(mathematics)<http://en.wikipedia.org/wiki/Matrix_%28mathematics%29>
> >.
> > > > J is a MIMD <http://en.wikipedia.org/wiki/MIMD> language."
> > > > See:
> > > > http://en.wikipedia.org/wiki/MIMD
> > > >
> ----------------------------------------------------------------------
> > > > For information about J forums see
> http://www.jsoftware.com/forums.htm
> > > >
> > >
> > >
> > >
> > > --
> > > Devon McCormick, CFA
> > > ^me^ at acm.
> > > org is my
> > > preferred e-mail
> > > ----------------------------------------------------------------------
> > > For information about J forums see http://www.jsoftware.com/forums.htm
> > >
> > > ----------------------------------------------------------------------
> > > For information about J forums see http://www.jsoftware.com/forums.htm
> > >
> >
> >
> >
> > --
> > Devon McCormick, CFA
> > ^me^ at acm.
> > org is my
> > preferred e-mail
> > ----------------------------------------------------------------------
> > For information about J forums see http://www.jsoftware.com/forums.htm
>
> --
> regards,
> ====================================================
> GPG key 1024D/4434BAB3 2008-08-24
> gpg --keyserver subkeys.pgp.net --recv-keys 4434BAB3
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
>
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